Portable prosthetic hand with soft pneumatic fingers

ABSTRACT

A finger actuator, includes a plurality of fluidically interconnected inflatable chambers, wherein each chamber comprises outer walls having an embedded extensible layer selected to constrain radial expansion and freestanding inner walls; and an inextensible layer connected to the chambers at a base of the chambers, the inextensible layer comprising a flexible polymer and having an embedded inextensible layer that extends along the length of the finger actuator.

CROSS-REFERENCE(S) TO RELATED APPLICATIONS

The present application is a continuation application of and claims thebenefit of priority to U.S. application Ser. No. 14/685,126, filed Apr.13, 2015, now U.S. Pat. No. 9,687,362, which claims the benefit of U.S.patent application Ser. No. 61/978,412 filed on Apr. 11, 2014, thecontent of which are hereby incorporated by reference herein in theirentirety.

TECHNICAL FIELD

This technology relates generally to prosthetic devices. In particular,this invention relates to a hand prosthesis including soft pneumaticfingers.

BACKGROUND

There are over one half million people with upper limb amputations inthe United States as of 2014. The options for prosthetic devices include(a) passive/cosmetic devices that are ascetically appealing, but whichprovide little functionality, and (b) active/robotic devices that canassist with some natural motions. Despite the clear advantages of anactive/robotic device, only a third of those patients who might benefitactually use an active prosthesis. While robotic prosthesis can providestrength and motor control, the high cost and weight serves as animpediment to its adoption.

A prosthesis device using light weight actuation methods that can bereadily incorporated into prosthetic devices is needed.

SUMMARY

The invention provides an actuator, acuator fabrication and designuseful in manufacture of prosthesis with soft components.

The prosthesis components include 1) fingers which arepneumatic/hydraulic actuators that bend when filled with pressurizedgas/liquid from compressors/pumps located in the housing of the hand,and 2) a control system which uses the compressors/pumps to pressurizethe fingers.

In one aspect, a finger actuator includes a plurality of fluidicallyinterconnected extensible segments separated from adjacent extensiblesegments by a flexible, inextensible hinge, wherein the extensiblesegments comprise at least one fluidically interconnected inflatablechamber, and the extensible segments comprise an outer wall selected toconstrain radial expansion and a freestanding inner wall; and aninextensible layer connected to the extensible segments at a base of theextensible segments, the inextensible layer comprising a flexiblepolymer and having an embedded inextensible layer that extends along thelength of the finger actuator.

In one or more embodiments, the plurality of extensible segmentsincludes 3-6 segments.

In any preceding embodiment, at least one extensible segment includestwo fluidically interconnected chambers, and for example, the at leastone extensible segment has two inner walls at opposing ends of thesegmentand the two fluidically interconnected chambers are locatedproximate to the inner walls.

In any preceding embodiment, the flexible, inextensible hinge isintegral with the inextensible layer.

In any preceding embodiment, the outer wall selected to constrain radialexpansion comprises an embedded extensible layer.

In any preceding embodiment, the extensible segments are made of asilicone rubber.

In any preceding embodiment, the extensible fabric includes spandexfabric, polyamide, or elastane.

In any preceding embodiment, the embedded inextensible layer includescotton, paper, or polyester layers.

In any preceding embodiment, the inextensible layer is made of the samematerial as the extensible segments, or the inextensible layer is madeof a different material than the extensible segments.

In any preceding embodiment, the chambers are molded.

In one aspect a prosthetic hand includes a base and a plurality offinger actuators according to any embodiment described herein.

In one or more embodiments, the prosthetic hand further includes atleast one air compressor coupled for pressurization of at least onefinger actuator.

In one or more embodiments, the prosthetic hand further includes atleast one valve for reversibly coupling the air compressor to at leastone finger actuator.

In any preceding embodiment, the prosthetic hand further includes amicroprocessor for receiving input from a sensor capable of readingmuscle voltage.

In any preceding embodiment, the microprocessor provides instructions tothe valve in response to a signal received from the sensor.

In another aspect, a method of operating a prosthetic hand includesproviding a prosthetic hand according to any embodiment describedherein; and providing instructions to the valve to open, wherein airpressure from the air compressor pressurizes at least one fingeractuator, thereby causing the finger actuator to bend.

In one or more embodiments, the instruction is in response to a signalreceived from the sensor.

In another aspect, a method of making a finger actuator includesintroducing an elastic reinforcement layer into each of a plurality ofmold chambers; positioning a lost wax member along the length of themold and spanning across each of the mold chambers; filling the moldwith an elastomeric material and curing the elastomeric material; beforeduring or after curing the elastomeric material, providing aninextensible layer to the base of the mold chambers; and after curingthe elastomeric material, heating the cured finger actuator to melt thelost wax member.

These and other aspects and embodiments of the disclosure areillustrated and described below.

It is contemplated that any embodiment disclosed herein may be properlycombined with any other embodiment disclosed herein. The combination ofany two or more embodiments disclosed herein is expressly contemplated.

BRIEF DESCRIPTION OF THE DRAWING

The invention is described with reference to the following figures,which are presented for the purpose of illustration only and are notintended to be limiting.

In the Drawings:

FIG. 1 is a schematic representation of a hand prosthesis having softpneumatically activated fingers according to one or more embodiments.

FIGS. 2A and 2B are perspective and cross-sectional illustrations,respectively, of a finger actuator according to one or more embodiments.

FIG. 2C is a cross-sectional schematic illustration of actuation of afinger actuator according to one or more embodiments.

FIGS. 3A and 3B are schematic cross-sectional illustrations of a fingeractua tor along the (A) lateral and (B) longitudinal dimension accordingto one or more embodiments.

FIGS. 4A-4D are a series of photographs illustrating a fabricationprocess for a finger actuator according to one or more embodiments.

FIG. 5 illustrates the experiment used to test the strength of theactuators.

FIG. 6 is a plot of weight (g) v. pressure (psi) for a finger actuatoraccording to one or more embodiments of the invention and for twocomparison actuators.

FIG. 7 is a schematic illustration of the control system of a robotichand according to one or more embodiments.

FIG. 8 is a schematic illustration of a prosthetic hand includingcontrol system according to one or more embodiments.

DETAILED DESCRIPTION

A prosthesis device using light weight actuators that can be readilyincorporated into prosthetic devices is described. FIG. 1 is a schematicillustration of a prosthetic device for a hand according to one or moreembodiments. The prosthesis includes soft fluidically, e.g.,pneumatically, activated actuators 100 (“finger actuators”) that areintegrated into a base 110. The soft actuators are configured to actuatefor gripping such as a three-point grip, i.e. a grip imitating the oneachieved by a natural hand when the thumb, index and long fingers gripan object. The base can be attached to a sleeve 120 that can accommodatethe base and permit a turning or swiveling motion that approximateswrist movement. The sleeve can house air compressors 130 for actuationof the soft actuators and a battery power source 140 to run thecompressors. Compressors/pumps are used to inflate the actuators.Optionally, some or all of the processing components can be housed inthe base.

Finger Actuators

The actuator includes an extensible elastomeric top layer bonded to aninextensible bottom layer. The inextensible layer can include a flexiblepolymer that has a restraining element, such as paper or mesh, embeddedin the layer.

The actuators employ an extensible fabric to increase the toughness ofthe elastomer used for the fingers. Since most compressors are limitedin their output pressure, the actuators according to one or moreembodiments maximize their exerted forces at lower pressures. To achievethis, soft elastomers, which require less stress to achieve a givenstrain, as compared to stiff elastomers, are reinforced using anextensible fabric. By reinforcing the soft elastomer, the effectivetoughness of the actuator increases (e.g., withstands larger pressures)and therefore exerts higher forces. The extensible fabric can either bein the form of a woven mesh (e.g., spandex, polyester-polyurethanecopolymers or other combinations of elastic polymer meshes (e.g.,silicone, polyurethane, polyamide, elastane)).

Both the upper extensible portion and the lower inextensible layerincludes flexible polymers, and can include for example elastomers. Theelastomeric layer can be made using conventional elastomeric polymers,such as silicone rubber. Elastomers with low stiffness will providelarger amplitude of motion for a given pressure, as compared to stifferelastomers. Stiffer elastomers, however, will provide a larger range offorces (before bursting due to over-pressurization).

The extensible top layer consists of inflatable chambers that allow theactuator to bend when pressurized. The bending motion results from adifference in elasticity between the elastomeric materials used for theinflatable chambers and an internally-embedded inelastic fabric locatednear the bottom of the actuator. FIG. 2 illustrates the components andmode of actuation of the finger actuator. FIG. 2A provides a perspectiveview of the finger actuator design having a plurality of chambers, eachof which can function as a finger joint, secured to an inextensiblebase. FIG. 2B is a cross-sectional view of the actuator showing theindividual chambers, with free side walls, and secured to a inelastic,e.g., reinforcing sheet embedded, layer. FIG. 2C illustrates themechanism of actuation. Pressure (gas or liquid) expands the chambers,which are prevented from radial expansion due to the inextensible layerand the thicker outer walls that prevent radial expansion. Expansiontherefore occurs in the lateral direction and bending occurs. Whileshown here for chambers having flat sides, it is contemplated that theactuator chambers can be rounded, which would provide a more human-likeappearance and functionality. In addition, as is discussed hereinbelow,the finger actuator can employ an embedded extensible fabric (inaddition to or in lieu of thicker external walls) to limit radialexpansion. Additional details on the manufacture and use of suchactuator is found in application U.S. Ser. No. U.S.61/867,845, filedAug. 20, 2013, which is incorporated in its entirety by reference.

FIG. 3 is a schematic illustration of a finger actuator 300 according toone or more embodiments. FIG. 3A shows a lateral cross-sectional view ofone segment in the finger actuator. FIG. 3B shows a lateralcross-sectional view of a plurality of segments in the finger actuator.The finger segment includes an upper elastomeric section 310 having anextensible layer 320 embedded therein. The elastomer can be a lowstiffness silicone rubber elastomer such as EcoFlex silicone rubbers.EcoFlex rubber is very soft, very strong and very “stretchy”, stretchingmany times its original size without tearing and will rebound to itsoriginal form without distortion. In one or more embodiments, anelastomer having an elongation at break of at least 500%, at least 800%and up to and including 1000% or even higher or any range bounded by thevalues recited herein can be used. They can have a tensile strength ofgreater than 100 psi, greater than 200 psi, greater than or equal to 350psi or up to 500 psi or any range bounded by the values recited herein.The low stiffness and large extensibility enables the elastomer toexpand to large volumes at relatively low pressures. Exemplaryelastomers can have a Shore hardness of between 00-5 and A-100 or anyrange bounded by the values recited herein.

The upper elastomeric section 310 is secured to inelastic layer 330having an inextensible sheet 340 embedded therein. The inelastic layercan be made of the same elastomeric polymer as the upper layer 310, withthe additional stiffness arising from the incorporation of a reinforcinginextensible layer such as paper. In other embodiments, the inelasticlayer 330 can be made of a stiffer elasomeric material, such asElastosil silicone elastomer.

The upper elastomeric layer defines an open space 350 (shown in dashedlines to indicate that it is offset into the plane of the figure andwithin the chamber). The upper elastomeric layer also includes a channel360 that runs along the length of the chamber and spans the distancebetween adjacent chambers. Channel 360 is in fluid connection withadjacent chambers and with an external port for pressurizing thechamber. Each finger segment includes an outer wall, e.g., a roundedouter wall that mimics a human finger) and an interior wall that facesan adjacent finger segment. The inner wall is free standing, in that itis not joined to adjacent finger segment, except at a base locationwhere a channel fluidically connects the finger segments.

In one or more embodiments, the number of finger segment in the fingeractuator is selected to mimic the joint movement of a hand. In one ormore embodiments, the actuator contains 3-6 finger segments.

In one or more embodiments, the finger actuator includes additionallayers of fabric embedded in each finger segment to prevent undesiredradial expansion of the finger segment which may cause the actuator tobreak. The radial expansion of the actuator is constrained byapplication of a constraining fabric to the walls of the extensibleelastomeric top layer. For example, an expandable fabric, such as aspandex fabric, layer or even an inextensible layer can be introducedaround each actuation chamber exterior to control the expansion of thesechambers individually. In other embodiments, the restraining fabric canbe embedded in the elastomeric material making up the extensiblechambers. Examples of extensible fabrics are spandex, polyamide, andelastane. Examples of inextensible fabrics are cotton, paper, polyester.

In one or more embodiments, the open space 350 within the actuators maybe fabricated using a loss-wax approach, in which a wax mold of theinternal structure of the actuator is placed within a mold during thecuring of the elastomer. Subsequently the wax can be melted out of theactuator providing a void space for pressure to be supplied. See, e.g.,FIG. 4C.

Fabrication of the figure actuator is described with reference to FIG.4A-4D.

FIG. 4A is a photograph of the mold 400 used to manufacture the fingeractuator. Mold 400 includes a base having a curved surface, mimicking ahuman finger. The interior of the mold includes spacers 430 that definethe spacing between mold sections 402. The number of spacers can varyand is selected to provide the desired number of joints in the fingeractuator. The spacers also include a recess 401 that are sized toaccommodate wax mold 405. Similar recesses 401 can be located in themold walls.

Next the reinforcing fabric is lined into the mold. Reinforcingextensible fabric 410 is provided, as shown in FIG. 4B. Each moldsection 402 is provided with reinforcing fabric sized to fit. The fabricis inserted into the mold and pressed along the walls of the mold sothat the fabric lines the mold inner surface.

Next the wax internal structure is positioned within the mold. FIG. 4Cis a photograph of an exemplary wax mold 405 including a supporting beam421 (that runs along the length of the finger actuator's multiplesegments and which forms the interconnected channel of the finalactuator) and plates 420, 420′ (shown here positioned proximate to oneend of the finer segment and which forms the void spaces of the fingersegment of the final product). FIG. 4C further illustrates thepositioning of the lost wax mold 405 in a mold for manufacture of thefinger actuator. Plates 420, 420′ are positioned on either side of aspacer 430, which defines the ‘joint’ in the molded finger. The platesdesignate the void spaces of the finger actuator that will expand andinduce the bending motion upon pressurization. A pair of plates 420,420′ are positioned proximate to and on opposite sides of spacer 430.

The mold is then filled with an elastomer precursor, such as EcoFlexsilicone rubber and cured to produce a hardened body. The inelastic baselayer having an inextensible sheet embedded therein can be formedintegrally with the chambers, by pressing a final inextensible sheetinto the filled mold prior to curing. In this case, the base and thechambers are made of the same elastomeric polymer. In other embodiments,the inelastic base can be joined to the molded chambers after curing.For example, a polymer layer having an inextensible sheet embeddedtherein can be bonded to the molded chambers using a curable siliconeelastomer as adhesive. FIG. 4D is a photograph of the molded fingeractuator after removal from the mold.

After the elastomer is cured, the molded actuator is heated to melt thewax from the lost wax mold and create the voids and channelinterconnects of the actuator.

FIG. 5 shows a picture of an experiment used to test the strength of theactuators. This experiment was used to obtain the data shown in FIG. 6.The actuators were individually tested (separate from the body of thehand and separate from the portable control system). They were mountedat one end and pressurized (so they would bend), and various weightswere suspended from the actuators. The pressure at which the actuatorcould no longer hold a given weight was recorded and plotted. The datain FIG. 6 show the weight an actuator could hold (just like a fingerholding a weight) and the pressure required to hold that weight.

Three different actuators were evaluated.

A finger actuator reported in FIG. 6 as a series of round shaped datapoints corresponds with a pneumatic actuator as described in FIGS. 3 and4. The actuator is prepared using an EcoFlex silicone elastomer, aspandex extensible reinforcing material for the chambers and a paperinextensible reinforcing material for the base.

Comparison actuator #1 is reported in FIG. 6 as a series of diamondshaped data points. Comparison actuator #1 corresponds to a pneumaticactuator having the structure shown in FIG. 2 having a rectangularcross-sectional geometry, in which the outer walls are thicker than theinner walls and are not reinforced with an extensible material. Theactuator is prepared using an Elastosil silicone elastomer, which is astiffer elastomer than EcoFlex silicone rubber.

Comparison actuator #2 is reported in FIG. 6 as a series of squareshaped data points. Comparison actuator #2 corresponds to a pneumaticactuator having a rounded shape with three joints (similar to the fingeractuator), with the following differences. Comparison actuator #2 ismade from an Elastosil silicone elastomer, which is a stiffer elastomerthan EcoFlex silicone rubber. In addition, a spandex fabric layer wassewn around the exterior of the actuator to control the expansion of thechambers.

The data show that the finger recent actuator can hold more weight withless pressure compared to the design s of Comparison actuators #1 and#2, which means that the actuator is better suited for portableprosthetic devices limited to small air compressors that can generatesmall pressures.

Prosthetic Hand

In one or more embodiments, the finger actuator is secured to a handbase to provide a prosthetic hand. The finger actuator is secured usingmetal screws that immobilize a 3D printed holder for the fingers to thehand base. Other methods of securing the finger actuator arecontemplated.

Control System

A microprocessor controlled compressor controls the pressurization ofthe finger actuators. In use, a pneumatic manifold system can beemployed which would allow for a number of finger positions to begenerated with the same single pressurized air input. In one or moreembodiments, the user (e.g., an upper limb amputee) wears a myoelectricsensor which detects muscle movements in their upper arm, causing thecompressors to turn on/off. Myoeletric sensors work by sensing, usingelectrodes when the muscles in the upper arm move, causing an artificialhand to open or close. Other methods for providing signal input to theactuators is contemplated.

In addition, pneumatic manifolds can be used to obtain certaincombinations of actuation of the fingers for the prosthetic hand. Thisstrategy will greatly reduce the complexity of controlling theprosthetic hand compared to controlling each finger individually.Additional detail on pneumatic manifolds is found in co-pendingapplication PCT/US13/66164, filed Oct. 22, 2013, the contents of whichare incorporated entirely by reference.

For demonstration purpose herein, the control system is designed for auser to flip a switch to turn on or off the air compressors which arepowered by a battery.

Description of various control system components is provided withreference to FIGS. 7 and 8. The components can be housed in a sleeveconnected to the hand base or can be integrated, in whole or in part,into the hand base.

-   -   1) Battery: Rechargeable lithium battery provides mobile power        supply    -   2) Voltage converters: Two commercially-available voltage        converter chips take in the 7.4-volt battery power supply and        generate one 9-volt output and one 5-volt output to power other        components described below.    -   3) Air compressors: Two air compressors are controlled by a        small slide switch (not shown) which allows the user to turn        them on or off. The compressors take in air from the atmosphere        and pressurize it, sending it through tubing to the solenoid        valves.    -   4) Solenoid valves: The solenoid valves open or close the tubing        connecting the air compressors with the actuators. The user can        open the valve using a second electrical switch (separate from        the compressors). If the valve is open and the compressors are        turned on, the fingers will inflate. If the valve is closed, the        air will be blocked from entering or exiting the actuators.    -   5) Microcontroller: The microcontroller is used to control the        solenoid valves by reading a myoelectric sensor which will read        muscle voltage from the amputee. If the user flexes their        muscle, the microcontroller will read the signal and open the        solenoid valve/turn on the air compressors (thus causing the        fingers to bend). Additional methods for providing input to the        prosthesis are also contemplated.

The fully functional prosthesis can be worn by a user with an upper limbamputation. Myoelectric sensors placed on the upper arm or back musclescan determine when the amputee flexes their muscles. The signal can besent to the microcontroller which then turns on the air compressors andopens the solenoid valves. Various muscle flexing patterns result inopening various combinations of solenoid valves (thus resulting indifferent hand grip configurations). The user can recharge the batteryas needed.

As will be apparent to one of ordinary skill in the art from a readingof this disclosure, the disclosed subject matter can be embodied informs other than those specifically disclosed above. The particularembodiments described above are, therefore, to be considered asillustrative and not restrictive. Those skilled in the art willrecognize, or be able to ascertain, using no more than routineexperimentation, numerous equivalents to the specific embodimentsdescribed herein. The scope of the invention is as set forth in theappended claims and equivalents thereof, rather than being limited tothe examples contained in the foregoing description.

It is noted that one or more publications, patent application, patents,or other references are incorporated herein. To the extent that any ofthe incorporated material is inconsistent with the present disclosure,the present disclosure shall control.

Unless otherwise defined, used or characterized herein, terms that areused herein (including technical and scientific terms) are to beinterpreted as having a meaning that is consistent with their acceptedmeaning in the context of the relevant art and are not to be interpretedin an idealized or overly formal sense unless expressly so definedherein. For example, if a particular composition is referenced, thecomposition may be substantially, though not perfectly pure, aspractical and imperfect realities may apply; e.g., the potentialpresence of at least trace impurities (e.g., at less than 1 or 2%) canbe understood as being within the scope of the description; likewise, ifa particular shape is referenced, the shape is intended to includeimperfect variations from ideal shapes, e.g., due to manufacturingtolerances. Percentages or concentrations expressed herein can representeither by weight or by volume.

Although the terms, first, second, third, etc., may be used herein todescribe various elements, these elements are not to be limited by theseterms. These terms are simply used to distinguish one element fromanother. Thus, a first element, discussed below, could be termed asecond element without departing from the teachings of the exemplaryembodiments. Spatially relative terms, such as “above,” “below,” “left,”“right,” “in front,” “behind,” and the like, may be used herein for easeof description to describe the relationship of one element to anotherelement, as illustrated in the figures. It will be understood that thespatially relative terms, as well as the illustrated configurations, areintended to encompass different orientations of the apparatus in use oroperation in addition to the orientations described herein and depictedin the figures. For example, if the apparatus in the figures is turnedover, elements described as “below” or “beneath” other elements orfeatures would then be oriented “above” the other elements or features.Thus, the exemplary term, “above,” may encompass both an orientation ofabove and below. The apparatus may be otherwise oriented (e.g., rotated90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly. Further still, in thisdisclosure, when an element is referred to as being “on,” “connectedto,” “coupled to,” “in contact with,” etc., another element, it may bedirectly on, connected to, coupled to, or in contact with the otherelement or intervening elements may be present unless otherwisespecified.

The terminology used herein is for the purpose of describing particularembodiments and is not intended to be limiting of exemplary embodiments.As used herein, singular forms, such as “a” and “an,” are intended toinclude the plural forms as well, unless the context indicatesotherwise.

It will be appreciated that while a particular sequence of steps hasbeen shown and described for purposes of explanation, the sequence maybe varied in certain respects, or the steps may be combined, while stillobtaining the desired configuration. Additionally, modifications to thedisclosed embodiment and the invention as claimed are possible andwithin the scope of this disclosed invention.

What is claimed is:
 1. A finger actuator, comprising: a plurality offluidically interconnected extensible segments, wherein: each extensiblesegment comprises two inner walls at opposing ends of the extensiblesegments that allow expansion of the extensible segment in the lateraldirection and an outer wall that is thicker than the inner walls toprevent radial expansion of the extensible segment; and each extensiblesegment comprises two fluidically connected inflatable chambers locatedproximate to the inner walls; and an inextensible layer connected to theplurality of fluidically interconnected extensible segments at a base ofthe extensible segments, the inextensible layer comprising a flexiblelayer and an inextensible material that extends along the length of theplurality of fluidically interconnected extensible segments.
 2. Thefinger actuator of claim 1, wherein the plurality of extensible segmentscomprises 3-6 segments.
 3. The finger actuator of claim 1, wherein thefinger actuator further comprises a hinge integrally molded with thefluidically interconnected extensible segments.
 4. The finger actuatorof claim 3, wherein the hinge is connected to the inextensible layer toform a flexible, inextensible hinge.
 5. The finger actuator of claim 1,wherein the extensible segments are comprised of a silicone rubber. 6.The finger actuator of claim 1, wherein the inextensible materialcomprises cotton, paper, or polyester layers.
 7. The finger actuator ofclaim 1, wherein the flexible layer of the inextensible layer iscomprised of the same material as the extensible segments.
 8. The fingeractuator of claim 1 wherein the flexible layer of the inextensible layeris comprised of a different material than the extensible segments. 9.The finger actuator of claim 1, wherein the two fluidicallyinterconnected chambers are molded.
 10. The finger actuator of claim 1,further comprising a hand base, wherein the finger actuator is securedto the hand base at one end of the finger actuator.
 11. The fingeractuator of claim 10, wherein the hand base comprises an air compressor,the air compressor fluidically connected to the secured finger actuator.12. The finger actuator of claim 11, further comprising a valve forreversibly connecting the air compressor to the secured finger actuator.13. The finger actuator of claim 12, wherein the hand base furtherhouses a microprocessor for receiving input from a sensor andtransmitting instructions to open or close the valve in response to theinput.
 14. A method of operating a finger actuator comprising: providinga first finger actuator secured to a hand base, wherein the fingeractuator comprises: a plurality of fluidically interconnected extensiblesegments, wherein each extensible segment comprises two inner walls atopposing ends of the extensible segments that allow expansion of theextensible segment in the lateral direction and an outer wall that isthicker than the inner walls to prevent radial expansion of theextensible segment, and each extensible segment comprises twofluidically connected inflatable chambers located proximate to the innerwalls; and an inextensible layer connected to the plurality offluidically interconnected extensible segments at a base of theextensible segments, the inextensible layer comprising a flexible layerhaving an inextensible material that extends along the length of theplurality of fluidically interconnected extensible segments; andproviding instructions to a valve housed in the hand base to open,wherein air pressure from an air compressor housed in the hand basepressurizes at least one finger actuator, thereby causing the fingeractuator to bend.
 15. The method of claim 14, wherein the instruction isin response to a signal received from a sensor.
 16. The method of claim14, further comprising a second finger actuator located at a position ofthe hand base spaced apart and opposed to the first finger actuator. 17.The method of claim 16, wherein the first finger actuator and the secondfinger actuator are pressurized and the combined pressurization of thefirst finger actuator and the second finger actuator provides a grippingmotion.